ENABLING A TRACTOR TO HAUL HEAVY LOADS.
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First Published Details of a New Carrimore Drawbar Device Especially Designed for Use with the Fordson Tractor.
THE EMPLOYMENT of the Fordson tractor as a road-haulage unit is in"creasing at a rapid pace, and for many classes of work it is proving most satisfactory. As a unit, however, it has one failing, and this is that, owing to its light weight, the adhesion between its driving wheels and the surface of the road is not always all that could be desired.
To assist in obtaining better adhesion, it is a practice to employ rear driving wheels of Considerable weight, and this certainly helps to a considerable extent ; but even with an equipment of this nature there are places, such, for inStance, as the slope leading to Blackfriars Bridge, where the road surface, combined with the gradient, almost forbids the hauling of a heavily laden trailer in the ordinary way.
Realizing that there is a considerable future for a light trailer of the Fordson type, if the adhesion can still further be improved, Carrimore Six Wheelers, Ltd., of Carrimore Works, High Road, Great North Road, Finchley, London, N.12, have recently produced an interesting type of trailer unit in which the drawbar is so arranged that any desired portion of the load on the front wheels of the trailer can be transferred to the foot, or towing attachment, of the Fordson tractor. It also enables the drawbar of the trailer to be presented at the height of• the tractor and elevates the drawbar to a position suitable for man-handling when this is required.
So far ftS the trailer portion is concerned, this is practically standard, with the exception that two quarter-elliptic laminated springs are mounted on the front of the trailer frame, their forward ends being shackled to a cross-piece, the centreof which is threaded for the reception of a vertical screw Supported by a channel-steel inverted vee on the drawbar. The last-named is ,pivoted to the centre of the front axle of the trailer, and the ordinary road springs of the trailer are secured at their rear ends.
A hand wheel at the top of the vertical screw on the drawbar permits the screw to be turned to any desired extent, and in doing so it raises the front ends of the quarter-elliptic springs, at the same time tending to force down the drawbar, which action is resisted, due to the fact that the drawbar is coupled to the tractor. The screw being mounted Midway along the drawbar, the imposing on the drawbar of a 2-ton load at this point will cause the addition of a ton load to the rear of the tractor.
In ordinary practice, very little loading indeed is necessary, but in the case of wheel slip occurring, a couple of turns of the screwed hand wheel is usually sufficient to ensure adhesion.
It will be realized that a considerable bending moment is exerted tin the channel-steel drawbar, and to prevent this giving under . the strain it is provided with a stout tiebar.
The Carrimore Adheser, as the device is termed, is semi-automatic in action, for the act of loading the trailer by depressing the ordinary road springs, also lowers the anchorages of the quarterelliptic springs, thus automatically transferring to the tractor about 50 per cent. of the load, which ratio can be altered at will to suit the varying conditions of the road surface.
In our close-up illustration of the device, the shackles on the quarter-elliptic springs are shown as pointing at an angle towards the rear, but in the latest form they will point at an angle to the front; this is to overcome the ektra loading effect which formerly occurred when the trailer wheels dropped into potholes, etc.
The device has recently been tested privately by the road transport chiefs of some of the leading railway companies and has electively proved its merits_ Trials on Blackfriars Bridge with gross loads of 10 tons have proved the effectiveness of the Adheser in maintaining a grip on the surface at parts where taCking 'methods had previously to be em played.
The complete equipment, carrying net loads of Stone and working on ordinary cominercial contracts; can be seen-...in
• Iionden by appointment with the Maim. facturers. • —
The novel features of the device, together with that which provides for the: progress of the outfit through a pot-hole. without temporarily altering the ratio of the weight on the foot of the tractor, have been provisionally protected, and the Adheser alone can be fitted to any make of four-wheel trailer at a cost of approximately £20.